Medical injector with post-autoreconstitution dose setting and autoplunger drive

ABSTRACT

A medical injector is provided herein having a body; a reservoir containing first and second mixable component; a stopper; a plunger; a spring disposed to advance the plunger; a first releasable retainer for releasably retaining the plunger in a first state against force of the spring; a first trigger for causing the first releasable retainer to release the plunger; a second releasable retainer for releasably retaining the plunger in a second state against force of the spring; and, a second trigger for causing the second releasable retainer to release the plunger. The spring causes the plunger to advance so that the stopper traverses at least a predetermined extent of advancement thereby causing mixing of the first and second mixable components. Advantageously, with the subject invention, a medical injector is provided which allows for autoreconstitution with subsequent dose setting and autoplunger activation being activated by separate triggers.

FIELD OF THE INVENTION

This invention relates to medical injectors with automatically drivenplungers and, more particularly, to medical injectors with automaticallydriven plungers which permit dose setting.

BACKGROUND OF THE INVENTION

Certain drugs or medicaments (those terms being used interchangeablyherein) are preferably provided in powder or dry form (such as alyophilized form), and require reconstitution prior to administration.Lyophilized drugs, for example, typically are supplied in a freeze-driedform that needs to be mixed with a diluent to reconstitute the substanceinto a form that is suitable for injection. Medicaments may also beprovided in other dry or powder form that require reconstitution.

In addition, drugs may be provided as multipart systems which requiremixing prior to administration. For example, one or more liquid (e.g.,flowable (slurry or liquid)) components, and/or dry (e.g., powdered orgranular) components may be provided in a drug container or deliverydevice which require mixing prior to administration. The components canbe mixed and used to form various administratable drugs, such asinsulin.

Prior art devices have been developed that provide a wet component(e.g., liquid) and a dry component (e.g., powder) in separate chambersof a common container with the container being configured to permit theflow of the wet component to the dry component to cause mixing thereofin preparing an administratable solution for injection. U.S. Pat. No.4,874,381 to Vetter is directed to an injector having a barrelconfigured for mixing, while U.S. Pat. No. 4,968,299 to Ahlstrand et al.is directed to a drug cartridge having a barrel configured for mixing.Both Vetter et al. and Ahlstrand et al. disclose typical configurationsfor mixing where a bypass channel is formed in the barrel of the device.As such, the device must be specifically configured for mixing.

Manual force may be applied to a reconstitution device to cause themixing of the multiple components. In addition, autoreconstitutiondevices have been developed in the prior art which provide atrigger-activated automated reconstitution. U.S. Pat. No. 6,793,646 toGiambattista et al. is an example of an autoreconstitution device.

It is noted that autoinjectors are known in the prior art which may alsocause autoreconstitution. Autoinjectors, however, are trigger-activateddevices which not only cause autoreconstitution, but will also cause aneedle to pierce a patient's skin with subsequent automated plungerdrive causing fluid administration. Autoinjectors typically do not havedose settings. In addition, the needle is pre-mounted to the device.Examples of this type of device may be found in U.S. Published PatentApplication No. 2004/0133163 to Schiffmann and in U.S. Published PatentApplication No. 2007/0142769 to Griffiths et al.

U.S. Pat. No. 7,407,494 to Bostrom et al. discloses anautoreconstitution device which permits dose setting afterreconstitution and subsequent activation of an autoplunger drive whichcauses automatic plunger actuation resulting in dose administration. TheBostrom et al. device, thus, requires two activations: a firstactivation to trigger the autoreconstitution; and, a second activationto trigger the autoplunger drive. Bostrom et al. provides a singleactivator button for both actions. Failure or improper operation duringautoreconstitution could possibly prevent subsequent injection even ifreconstitution was successfully performed.

SUMMARY OF THE INVENTION

A medical injector is provided herein having a body; a reservoircontaining first and second mixable components, a stopper associatedwith the reservoir, a predetermined extent of advancement of the stoppercausing mixing of the first and second mixable components; adisplaceable plunger disposed in the body; a spring disposed to advancethe plunger; a first releasable retainer for releasably retaining theplunger in a first state against force of the spring; a first triggerfor causing the first releasable retainer to release the plunger; asecond releasable retainer for releasably retaining the plunger in asecond state against force of the spring; and, a second trigger forcausing the second releasable retainer to release the plunger. Thespring causes the plunger to advance from the first state to the secondstate. The plunger engages the stopper during the advancement from thefirst state to the second state so that the stopper traverses at leastthe predetermined extent of advancement thereby causing mixing of thefirst and second mixable components. Advantageously, with the subjectinvention, a medical injector is provided which allows forautoreconstitution with subsequent dose setting and autoplungeractivations, the autoreconstitution and the autoplunger activationsbeing activated by separate triggers.

These and other features of the invention will be better understoodthrough a study of the following detailed description and accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a medical injector formed in accordancewith the subject invention;

FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1;

FIGS. 3-6 show a plunger and a second retainer configuration useablewith the subject invention;

FIGS. 7-8 show a dose ring useable with the subject invention;

FIG. 9 shows schematically a dose setting configuration useable with thesubject invention; and,

FIG. 10 shows a configuration of the second retainer and dose ringuseable with the subject invention.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the Figures, the subject invention provides a medicalinjector 10 which allows for dose setting after autoreconstitution andprior to autoplunger drive. In particular, the medical injector 10 isconfigured to permit mounting of a needle 12 thereto. The medicalinjector 10 may be in the form of any medical injector, such as asyringe or pen injector, which is capable of reconstituting mixablecomponents accommodated therein into an administrable liquid. Themedical injector 10 may be a single- or multiple-dose device.

The needle 12 may be in any form. Preferably, the needle 12 includes ahub 14 to which is affixed a needle cannula 16. Distal end 18 of theneedle cannula 16 is formed for insertion into a patient, while proximalend 20 may optimally be sharpened. The hub 14 may be formed withmounting features 22, such as threads, for mounting onto the medicalinjector 10, as described below.

As used herein, the term “distal”, and derivatives thereof, shall referto a direction toward a patient during use, while the term “proximal”and derivatives thereof, shall refer to a direction away from a patientduring use.

The medical injector 10 includes a body 24 which may be formed of one ormore components. The medical injector 10 also includes a needle mountingsurface 26 having features 28 for mounting the needle 12 thereto. Thefeatures 28 may be of any known type for mounting the needle 12including features for creating a cooperating mechanical lock with theneedle 12, particularly for cooperating with the mounting features 22,such as threads, bayonet lock members, detents, grooves, and so forth,and/or frictional engagement with the hub 14, such as through a taperedLuer configuration.

The medical injector 10 is an autoreconstitution device which, as shownin FIG. 2, includes at least first and second mixable components 30, 32in an initial state. A reservoir 34 is disposed in the body 24 foraccommodating the first and second mixable components 30, 32. At leastone stopper 36 is associated with the reservoir 34 configured such thatdistal advancement of the stopper 36 over a predetermined distance shallcause mixing of the first and second mixable components 30, 32. Anyknown arrangement for allowing such mixing may be utilized. By way ofnon-limiting example, the first and second mixable components 30, 32 maybe separated by a secondary stopper 38. The secondary stopper 38 dividesthe reservoir 34 into first and second chambers 40, 42, respectively,accommodating the first and second mixable components 30, 32. A septum44 seals off the distal end of the first chamber 40, while the stopper36 is positioned to seal off the proximal end of the second chamber 42.Preferably, if a dry component is used as one of the mixable components,the dry mixable component is located in the first chamber 40.

One or more by-pass channels 46 are formed in the wall of the reservoir34. In an initial state, as shown in FIG. 2, the secondary stopper 38 islocated at least partially proximally of the by-pass channels 46 so asto define a seal between the first and second chambers 40, 42 and todefine a seal between the second chamber 42 and the by-pass channels 46.With distal advancement of the stopper 36, and with the second mixablecomponent 32 being wet and generally incompressible, force of movementof the stopper 36 is transmitted to the secondary stopper 38 through thesecond mixable component 32. With sufficient distal movement of thesecondary stopper 38, the second chamber 42 comes into communicationwith the by-pass channels 46, thus allowing the second mixable component30 to be urged into the first chamber 40 with further distal movement ofthe stopper 36. With reference to FIG. 2, with sufficient distaladvancement of the stopper 36, the second chamber 42 is collapsed withnone or substantially none of the second mixable component 32 remainingtherein. In addition, the secondary stopper 38 is located so as todefine a seal between the first chamber 40 and the by-pass channels 46.The first and second mixable components 30, 32 are mixed within thefirst chamber 40, such as through agitation of the medical injector 10,so as to produce an injectable solution, ready for injection.

As will be recognized by those skilled in the art, other arrangementsfor permitting reconstitution may be utilized. In addition, more thantwo-part systems, such as three-part, and so forth, systems may beutilized. Active medical ingredients may be included in one or both ofthe first and second mixable components 30, 32. The first mixablecomponent 30 may be dry (e.g., a powder or granular substance) and/or aliquid (e.g., flowable (slurry or liquid)). As mentioned above, thesecond mixable component 32 is preferably only a wet flowable componentsuch as a liquid or slurry.

It is preferred that movement of the stopper 36 be automated to achieveautoreconstitution. Various trigger-activated autoreconstitutionconfigurations are known in the prior art, such as that disclosed inU.S. Pat. No. 6,793,646 to Giambattista et al., which is incorporated byreference herein in its entirety. As shown in FIG. 2, a spring 56 may beprovided to cause plunger 58 to drive forward. The plunger 58 actsagainst the stopper 36 in achieving autoreconstitution of the first andsecond mixable components 30, 32, as described above. The spring 56 mayact, via the plunger 58, to distally drive the stopper 36 from theinitial first position of FIG. 2. The spring 56 may be of any type,including coil or compression spring. Other types of biasing elementsmay be also utilized.

The plunger 58 is retained in the first position of FIG. 2 by any knownmanner of releasable retaining mechanism. A trigger may be provided torelease the retaining mechanism to cause autoreconstitution andadvancement of the plunger 58. As indicated above, U.S. Pat. No.6,793,646 to Giambatista et al. discloses an injector withtrigger-activated autoreconstitution where autoreconstitution isactivated by collapsing together two body parts of the injector. Thecollapsing effect causes release of the plunger and autoreconstitution.

Alternatively, as shown in FIG. 2, a trigger 60 may be slidably disposedin the body 24, and the plunger 58 may include one or more deflectablelatch tabs 62. In the initial first state of FIG. 2, the latch tabs 62have free ends 64 which interferingly engage ledges 66. Interengagementbetween the latch tabs 66 and the ledges 66 retains the plunger 58 inthe first state against force of movement of the spring 56. The trigger60 includes one or more arms 68 which define a smaller diameter than thelatch tabs 62. With sufficient distal advancement of the trigger 60,e.g. being caused by force being applied to proximal end 70 thereof, thearms 68 engage the latch tabs 62 and cause inward deflection thereof.With inward deflection of the latch tabs 62, the spring 56 is free todrive the plunger 58 distally and engage the stopper 36 in causingautoreconstitution.

As will be appreciated by those skilled in the art, other releasableretaining arrangements and triggers may be utilized for retaining theplunger 58 in the initial state and causing release therefrom. Forexample, a bayonet lock-type releasable retaining arrangement may beutilized which is triggered by rotating one or more portions of the bodyof the medical injector 10 or rotating an additional component, such asa dose setting knob. Copending applications PCT Application No.PCT/US2009/057439 and PCT Application No. PCT/US2009/057460 disclosereleasable retainer arrangements which are triggered by rotation topermit plunger advancement; these applications are incorporated byreference herein in their entireties.

The spring 56 is configured to advance the plunger 58 a predeterminedextent of movement. A second releasable retainer 70 is provided tointercept the plunger 58 along its course of advancement in stopping theplunger 58 at a second position. The second position is located so as toprevent the plunger 58 from traversing the entire predetermined extentof movement. In addition, the second position is located so as to permitthe plunger 58 to traverse a sufficient distance to drive the stopper 36a sufficient distance to achieve reconstitution.

With reference to FIGS. 3-6, the second releasable retainer 70 mayinclude stop block 72 having an opening 74 formed therethrough to permitpassage of plunger stem 76 of the plunger 58. The plunger stem 76 isaligned to engage the stopper 36 during use. The opening 74 is formedlarger than the cross-section of the plunger stem 76 such that the stopblock 72 is axially shiftable relative to the plunger stem 76 betweenblocking and open states. The stop block 72 is axially shiftable in adirection transverse to the direction of movement of the plunger 58. Inthe blocking state, as shown in FIGS. 3 and 4, the stop block 72 isformed to interferingly engage stop member 78 formed on the plunger 58with a portion of the plunger stem 76 passing through the opening 74. Inthe open state, as shown in FIG. 5, the stop block 72 permits the stopmember 78 to pass through the opening 74 with the plunger stem 76.

As shown in FIG. 6, in the initial first state, the stop member 78 isaxially spaced from the stop block 72. With the plunger 58 beingreleased from the first state, the plunger 58 axially advances with theplunger stem 76 passing through the opening 74. During this movement,the plunger 58 advances the stopper 36 at least a sufficient distance toachieve reconstitution. The stop block 72 is initially in the blockingstate. Eventual distal advancement of the plunger 58 causes the stopmember 78 to engage the stop block 72, as shown in FIG. 3. The point ofengagement between the stop member 78 and the stop block 72 is reachedprior to the entire predetermined extent of movement of the plunger 58for which the spring 56 is configured. Thus, the stop block 72 retainsthe plunger 58 in this second state against force of movement of thespring 56. Axial shift of the stop block 72 moves the stop block 72 tothe open state thus releasing the plunger 58 from the second state.

The stop block 72 is positioned to locate the second state at minimallya distance permitting autoreconstitution to be achieved with the plunger58 moving from the first state to the second state. Preferably,reconstitution of the first and second mixable components 30, 32 isconducted without the needle 12 mounted to the medical injector 10. Assuch, the reservoir 34 is not vented during the mixing. In this manner,the mixed components may be maximally compressed under force of thespring 56. With mounting of the needle 12 onto the medical injector 10,the reservoir 34 is vented thus permitting further distal advancement ofthe plunger 58. This secondary distal advancement may assist in priminga needle for use. It is preferred that autoreconstitution be completedprior to the stop member 78 coming into engagement with the stop block72. With subsequent mounting of the needle 12 onto the medical injector10, the reservoir 34 is vented, thus reducing the trapped volumetherein. This permits the stopper 36 to be further advanced under forceof movement of the spring 56 till trapped gases are purged. It ispreferred that the stop member 78 come into engagement with the stopblock 72 upon this secondary distal advancement.

Dose selection may be conducted upon initiation, during or afterautoreconstituion. Any configuration for dose selection may be utilized.By way of non-limiting example, and with reference to FIGS. 7 and 8, adose ring 80 may be provided with a plurality of axially and radiallyspaced-apart abutment surfaces 82 which represent different dose sizes.

The abutment surfaces 82 are axially alignable with one or moreengagement surfaces 84 formed on the plunger 58. One or more tabs 86 mayextend from the plunger 58 on which the engagement surfaces 84 may bedefined. It is preferred that the tabs 86 be formed to not be passablethrough the opening 74 of the stop block 72 in either the blocking oropen states. The dose ring 80 includes an aperture 87 which permitspassage of the plunger stem 76 and the stop member 78 therethrough.

With rotation of the plunger 58, the engagement surfaces 84 may beaxially aligned with different of the abutment surfaces 82 thus allowingfor dose selection. The engagement surfaces 84 are spaced from theabutment surfaces 82 with the plunger 58 being retained in the secondstate. The distance between the engagement surfaces 84, located with theplunger 58 being in the second state, and the selected of the abutmentssurfaces 82 will dictate the stroke length of the plunger 58 duringinjection and, thus, dictate the dose size. A greater distance willprovide a larger dose and, conversely, a smaller distance will provide asmaller dose. Once a dose is set, the needle 12 is inserted into apatient and the stop block 72 is urged from the blocking state to theopen state. Consequently, the plunger 58, under force of movement of thespring 56, is advanced distally and, in turn, forces the stopper 36distally to urge the injectable solution into the patient.Interengagement of the selected abutment surfaces 82 and the engagementsurfaces 84 limits the distal movement to produce the selected dose.Movement of the plunger 58 is automated under force of the spring 56thus producing an autoplunger drive.

As will be appreciated by those skilled in the art, the plunger 58 maybe caused to rotate by various configurations. For example, as shown inFIG. 9, one of more of the tabs 86 may be nested in slots 88 formed inan outer body portion 90. With rotation of the outer body portion 90,corresponding rotation of the plunger 58 may be achieved. Indicia 91(FIG. 1) may be located on the medical injector 10 to assist in dosesetting.

The stop block 72 is axially shifted through activation of secondtrigger 92. Preferably, the second trigger 92 is aninwardly-displaceable button formed on the body 24 and aligned to shiftthe stop block 72 from the blocking state to the open state with inwarddisplacement. One or more intermediary components may be utilized whichtransmit force from inward displacement of the second trigger 92 to thestop block 72.

With reference to FIG. 10, it is preferred that the dose ring 80 haveretaining clips 94 formed to snap receive the stop block 72 with theopening 74 and the aperture 87 being aligned so as to both permitpassage therethrough of the plunger stem 76. The dose ring 80 is formedto permit axial shifting of the stop block 72 between the blocking andopen states. A spring arm 96 may extend from the dose ring 80 to biasthe stop block 72 to the blocking state. Axial movement of the stopblock 72 to the open state is thus against biasing force generated bythe spring arm 96.

Dose selection may be conducted at any time prior to release of theplunger 58 from the second state. It is preferred that once a dose isset, axial alignment of the selected abutment surfaces 82 and theengagement surfaces 84 be maintained. Such an arrangement is disclosedin U.S. Pat. No. 6,793,646, which is incorporated by reference herein inits entirety. As shown therein, one or more tabs may be used to engageteeth or channels in a ratchet fashion.

To prevent premature release from the second state, as shownschematically in FIG. 3, one or more of the tabs 86 may be initiallyradially positioned to block the second trigger 92 from activation priorto dose selection with the plunger 58 being in the second state. In thismanner, the second trigger 92 is blocked from inward displacement and,thus, is blocked from shifting the stop block 72 from the blocking stateto the open state. With radial adjustment of the tabs 86 in selecting adose, the second trigger 92 may be freed for activation.

With the subject invention, a medical injector is provided with twodistinct triggers for causing autoreconstitution and autoplunger drive,respectively. Advantageously, dose selection is permitted afterautoreconstitution and prior to automated plunger drive.

What is claimed is:
 1. A medical injector comprising: a body; areservoir containing first and second mixable components, a stopperassociated with said reservoir, a predetermined extent of advancement ofsaid stopper causing mixing of said first and second mixable components;a displaceable plunger disposed in said body; a spring disposed toadvance said plunger; a first releasable retainer for releasablyretaining said plunger in a first state against force of said spring; afirst trigger for causing said first releasable retainer to release saidplunger; a second releasable retainer for releasably retaining saidplunger in a second state against force of said spring; and, a secondtrigger for causing said second releasable retainer to release saidplunger, wherein, said plunger is advanced from said first state to saidsecond state by said spring, said plunger engaging said stopper duringsaid advancement from said first state to said second state so that saidstopper traverses at least said predetermined extent of advancementthereby causing mixing of said first and second mixable components,wherein said second retainer includes a stop block axially shiftablebetween a blocking state and an open state, wherein, in said blockingstate, said stop block interferingly engages a stop member formed onsaid plunger, and, wherein, in said open state, said stop block permitspassage therethrough of said stop member, said shifting of said stopblock allowing said plunger to be released from said second state.
 2. Amedical injector as in claim 1, wherein, upon release of said plungerfrom said second state, said spring advances said plunger apredetermined distance.
 3. A medical injector as in claim 2, whereinsaid predetermined distance is selected prior to said plunger beingreleased from said second state.